The last name search, by default, uses an enhanced phonetic soundex. This means that spoken name sounds are coded to create a Search Results List that includes all names that sound like the name(s) you have entered in the Last Name Parameter box(s). This will create a Results List of names that will include some that are nowhere near the same spelling as the one you entered. The advantage of this search is that it casts a wider net and will include records when the name entered is misspelled or is spelled differently from the name in a record
By toggling the "Alpha Search" box you can change the search to alphabetical. This search is based solely on the alphabetical characters you enter in the Last Name Parameter box. All names beginning with the characters you have entered will be listed (e.g., if you enter "Smith" you will also see "Smithers", "Smithy", "Smithsonian", etc) on the Results Page. If you enter a character that differs from the name of record (due to your misspelling or a different spelling of the name of record) the record will be missed (the soundex search would list it if the name sound is still close)."